package com.itheima.homework;

import java.util.Random;

public class test08 {
    public static void main(String[] args) {
        String s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXXYZ0123456789";
        Random r = new Random();
        String s1 = "";
        for (int i = 0; i < 4; i++) {
            int a = r.nextInt(s.length());
            char c = s.charAt(a);
            s1 += c;
        }
        System.out.println(s1);
    }
}
